Data Set Information
DATA_SET_NAME HST S WFPC2 DERIVED ASTROMETRY 2002 V1.0
DATA_SET_ID HST-S-WFPC2-4-ASTROM2002-V1.0
NSSDC_DATA_SET_ID
DATA_SET_TERSE_DESCRIPTION
DATA_SET_DESCRIPTION Data Set Overview : This dataset contains astrometric data for eleven Saturn satellites. The data were obtained using the HST/WFPC2 over the period 1994-2002. The volume contains only derived products. PI: Richard G. French (Wellesley College) Objectives : The observations from which these results were derived were part of a long term investigation of Saturn's rings prior to Cassini's arrival in 2004. The primary intent of this specific portion of the investigation was to refine orbital information for Prometheus and Pandora. Observations made during the 1995-1996 Saturn Ring Plane Crossing led to the unexpected finding that the positions of both satellites varied significantly from the predictions based on the Voyager observations (BOSH&RIVKIN1996, NICHOLSONETAL1996, MCGHEEETAL2001, SYNNOTTETAL1983). Sufficient observations to produce astrometrically meaningful data for nine other satellites were obtained incidentally in the Prometheus-Pandora observing campaign. The data for those satellites is also included in this data set. Observation summary and conditions : For this investigation the primary new observations are from the ongoing HST WFPC2 campaign to observe the main rings of Saturn over the full range of ring tilt and phase angles visible from the Earth (1996-2002). These observations were made near opposition and quadrature. For completeness, HST WFPC2 archival observations of Saturn's rings taken in 1994-1995 were also used. The overall quality of the images used is excellent. Processing : See FRENCHETAL2003. Data : The data provided here are in ASCII tables. For each data file, a detached PDS label is provided containing additional information. Most users will prefer to focus on the PDS compliant data files in the DATA/EASYDATA/ subdirectory. These files and their labels contain all of the information in the original files provided by R. French. The original files are included for completeness and can be found in the DATA/SORCDATA/ subdirectory. The satellites for which data are included in this volume are: Dione, Enceladus, Epimetheus, Helene, Hyperion, Janus, Mimas, Pandora, Prometheus, Rhea, and Tethys. Satellite positions have been determined and are recorded in the individual table files by satellite. The data include the WFPC2 image name, the midpoint UTC time of the observation, the arcsec offsets from the center of the planet (RA*Cos(Dec) and DEC, with their corresponding formal uncertainties. Details of the observations and reduction techniques may be found in FRENCHETAL2003. Ancillary Data : Calibration data is not provided. SPICE SPK files containing ephemeris information for the HST during the period covered by this data set are included in the SPICE/ directory. Coordinate System : All geometric quantities appearing in the labels are in J2000 coordinates. In this coordinate frame, the z-axis points northward along the Earth's J2000 rotation axis and the x-axis points toward the First Point of Aries. All of the calculations are geocentric rather than 'HST-centric'. During peer review, Dr M. Evans noted this turns out to be a minor issue. He performed orbit fits to the Prometheus data. The resulting elements were effectivly the same whether using HST or the center of the Earth as the observation point. The differences in the derived orbital elements were much smaller than the associated errors.
DATA_SET_RELEASE_DATE 2003-06-03T00:00:00.000Z
START_TIME 1994-12-01T12:00:00.000Z
STOP_TIME 2002-12-18T12:00:00.000Z
MISSION_NAME HST
SATURN SMALL SATELLITE ASTROMETRY
MISSION_START_DATE 1990-04-08T12:00:00.000Z
1994-12-01T12:00:00.000Z
MISSION_STOP_DATE N/A (ongoing)
2005-01-14T12:00:00.000Z
TARGET_NAME DIONE
ENCELADUS
EPIMETHEUS
HELENE
HYPERION
JANUS
MIMAS
PANDORA
PROMETHEUS
RHEA
TETHYS
TARGET_TYPE SATELLITE
INSTRUMENT_HOST_ID HST
INSTRUMENT_NAME WIDE FIELD PLANETARY CAMERA 2
INSTRUMENT_ID WFPC2
INSTRUMENT_TYPE CAMERA
NODE_NAME Planetary Rings
ARCHIVE_STATUS ARCHIVED
CONFIDENCE_LEVEL_NOTE Confidence Level Overview : High. Review : These data completed peer review on August 13, 2004. Members of the peer review panel were: Nick Cooper (Queen Mary, University of London), Luke Dones (South west Research Institute, Mike Evans (Queen Mary, University of London), Richard French(Wellesley College), Robert Jacobson (JPL), and Carl Murray (Queen Mary, University of London).
CITATION_DESCRIPTION French, R.G., C.A. McGhee, L. Dones, and J.J. Lissauer, Saturn Satellite Astrometry with WFPC2: 1994-2002, HST-S-WFPC2-4-ASTROM2002-V1.0, USA_NASA_PDS_ASTROM_0001, NASA Planetary Data System, 2003.
ABSTRACT_TEXT not applicable
PRODUCER_FULL_NAME MITCHELL K. GORDON
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